Driven,headed,and screw-threaded fastenings



Dec. 23, 1969 J. F. HAINNY ET AL v 3,485,132

DRIVEN, BEADED; AND SCREW-THREADED FASTENINGS Filed Aug. 2, 1965 2 Sheets-Sheet 1 FIG. I

PUSTULAR COATING PRESSURE-RUPTURABLE CAPSULES 2 E250 M|cRONs-1 PROTECTIVE LIQUID 27,

POLYMERIC PROTECTIVE FILM MATERIAL 3O FASTENING BODY (RIVET) FAY'NG SURFACE FIG. 2

l. RIVET HEAD CAPSUbES CONTAINING RIVET SHANK PROTECTIVE LIQUID INVENTORS JOHN F. HANNY ROBERT J. SHAFER JOHN G. WHITAKER THEIR ATTORNEYS Dec. 23, 1969 J. F. HANNY ET AL 3,485,132

DRIVEN, BEADED, AND SCREW-THREADED FASTENINGS Filed Aug. 2, 1965 2 Sheets-Sheet 2 FIG. 3 V

PRESSURE RELEASED COATING FIG.5. FIG.4

INVENTORS JOHN F. HANNY ROBERT J. SHAFER JOHN G. WHITAKER 8* m a; a

THEIR ATTORNEYS United States Patent 3,485,132 DRIVEN, HEADED, AND SCREW-THREADED FASTENINGS John F. Hanny, West Carrollton, Robert J. Shafer, Dayton, and John G. Whitaker, Union, Ohio, assignors to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Filed Aug. 2, 1965, Ser. No. 476,381 Int. Cl. F16b 19/06, 19/04 US. Cl. 85-1 1 Claim ABSTRACT OF THE DISCLOSURE use handling.

This invention relates to driven, headed, and screwthreaded fastenings, particularly to those yielding liquid protecting matter when their faying surfaces are forced into jamming relation to the material to be fastened.

The invention provides fastenings having a pustular dusting of minute and closely-spaced rotund or substantially rotund capsules containing droplets of the protective liquid, the capsules being retained on the faying surfaces of the fastenings partially embedded in a thin foundation film matrix of adhesive material. The outward contours of the capsules for the most part stand free of said embedding matrix material, forming a knobby pattern, and the pattern layer is draped with a thin layer of abrasion-resisting film material to protect the capsules from being broken or brushed off by before-use handling.

The term pustular is used to imply a protected protuberant knobbiness of a liquid droplet distribution on the fastening, and further to imply that the liquid droplets are released individually by pressure applied to the pustule protuberance. A distinction is made between a blister, which merely is exuded liquid under a skin, and a pustule, which is capsular-held liquid beneath a skin.

The term capsular indicates that the droplets of liquid are individually encased in their own wall material.

The term embedded is used to indicate that the individual capsules are not completely buried in the matrix but are exposed as protuberant knobs.

The term draped is used to indicate that the abrasionresistant polymeric material film follows the contours of the protuberant capsules, so that, even though sheathed, they are individually mechanically exposed for breaking or squeezing forces or pressures to cause their rupture.

It is acknowledged that it has been known heretofore to supply fastenings with a liquid which is released upon their use in pressure-fastening operations. This invention is an improvement in respect to the means for supplying the protective liquid so that it is evenly distributed over the fastening before and during use, yet the liquid is retained physically concealed to touch, before use, in minute pressure-rupturable capsules arranged beneath an investment sheath, which furnishes storage and handling protection for the capsules, yet leaves them from being completely submerged individually by the investment, which would tend to keep them from easily bursting on applied jamming and torque forces encountered in a fastening operation.

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The term setting or setting operation refers to the pounding of a fastening to deform it, or to the use of a continuous driving force to deform the fastening material or to deform the workpiece to which the fastening is applied, or to any of the forces used in any combination or in any sequence that may be required in the end use.

Particularly the invention is directed to fastenings which have faying surface relation with the materials to be fastened and which require jamming pressures or shearing forces between the faying surfaces in the setting and fastening operation. Among such fastenings are rivets, bolts, screws, nails, wedges, and the like, which require hammering or torque forces to set them in position. The torque forces naturally are associated with screw thread constructions. Within the term fastenings are included items which do not necessarily fasten two workpiece materials together but include hooks, studs, eye-bolts, cleats, and spikes, which must be attached to a supporting workpiece and which in turn find their utility in supporting or acting on other objects.

The most important use now known for the invention is the provision of the release of liquid anti-corrosion and sealant material in the fastening together of overlapping metal plates, particularly as in the use of a deformable rivet type of fastening, or in the use of screw bolts which may draw such metal plates together through torque action. It is quite common that the drawing of metal plates together damages them so that they are more easily subjected to corrosion, or different metals, when drawn together, may have some electrolysis relation with each other. Also, metal plates may have protective surfaces damaged by the insertion and setting of the fastening. It is at once apparent that the released liquid should be of such a character as to act not only as a corrosion-resistant material but as a sealant with or without corrosion-resistant properties, or lubricating properties, or all three properties in any manner. The liquid and the film materials may contain tracer materials which are radiant or which may be responsive to radiation to enable one to determine whether a particular fastening in place in a workpiece has been protected by the practice of this invention.

It has been found convenient to prepare the fastenings by a three-step method which consists in, first, spraying the faying surfaces of the fastening with an organic polymeric film-forming matrix material made into a. fast-drying varnish by a solution of it. in an organic evaporable solvent; second, dusting the so-coated faying surfaces with the minute capsules, while the matrix material coating is still tacky, so that the capsules embed themselves therein to a certain degree of depth; and, third, spraying a liquid solution of the abrasion-resistant film material over the capsules in an otherwise substantially smooth surface. The dimensions of coating and capsules are of such small measurements as to be tolerated in fastenings of the type associated with metal working with hand-operated or machine-operated driving or twisting tools. The total fabricated coating may be less than five mils in thickness.

The invention contemplates the use of oily protective liquids; that is to say, liquids which consist of oil or oil solutions or which consist of a dispersion of actve protective material in an oil vehicle, or an oil-like vehicle which itself may or may not have the protective properties. There are a great many ways in which to minutely encapsulate oily materials in an masse operations wherein the oily material of liquid nature (whether itself protective or merely acting as a vehicle for protective material) is dispersed as droplets in an aqueous manufacturing vehicle which contains the intended capsule wall material dissolved in it. Capsules so made may be as little as one to two microns in greatest dimension and as great as several hundred microns in greatest dimension. The contents of a capsule can be as much as 90% of the entire Weight of the capsule, which leaves for the weight of the wall material. This leaves the fastening with very little wall material debris left after the capsules are broken in use. The detritus of the capsule wall material is insignificant in the total capsular coating weight. Capsules from to 300 microns in diameter constitute the most suitable range for use with rivets, bolts, and screws which are of dimensions which are individually handled manually for insertion, and the best results have been obtained with capsules of 250 microns in average dimension. These dimensions may be changed as the occasion demands for extremely large or extremely small cfastenings, or under conditions of close fit. The rupture and release of the capsules undergoing jamming pressure must not require an undue amount of force per unit area to release the liquid contents. Where tight fits between the fastening and the aperture in which it is to be used are concerned, the capsules may be microscopic and be present in a fabricated layer only 25 microns in thickness. The total coating thickness of the protective layer should perhaps not exceed twice the thickness of the capsule layer.

A distinction should be made in the structure between the pustular coating of this invention, in which the droplets are individually protected in their own walls, and an inferior coating which is merely a dried emulsion of liquid droplets which are retained in a film material subject to interconnecting porosity and leakage through crazing of the film, which is a common characteristic of continuous polymer film structures. The structure of this invention is intentionally termed pustular because each capsule in the layer, in addition to being protected by the common protective film, is itself a sealed but rupturnable unit.

The invention finds an almost complete representation of its features in a very simple form in the treatment of fastenings in which a shanked and headed rivet 25 (FIGS. 1 and 2) is provided on the shank and underhead surfaces (the faying surfaces) with the pustular-capsule layer 26. Such rivets are utilized by insertion of the shank through a prepared aperture in the workpieces to be joined, or to whihc the rivet is joined in case the rivet is of the stud type, and the rivet is set into place by being jammed by pounding and pressure to deform it, so that the capsules on the under side of the head, on the middle of the shank, and on the upset deformed end of the shank are brought into great pressure relation with the faying surfaces of the workpiece material being fastened, with the result that the capsules are broken, leaving a large amount of liquid protective material to wet the surfaces in contact. Even though there is a tight fit between the rivet head, the shank, and the upset head on the deformed end of the rivet and the workpiece material fastened, there is sufiicient opportunity for the released liquid to become a more or less solid film by evaporation of the solvent and by oxidation and hydrolysis under proper circumstances with eligible materials. The vehicle in which the protective material is dispersed to form the contents of the capsule is provided with some means for drying and adhering any dispersed material in place where it is lodged between the faying surfaces.

Exemplary of the use of rivets treated with the novel pustular-capsule construction are those for use in the fastening of aluminum alloy plates to form airplane skins, in which there is an opportunity for electrolysis and corrosion to occur. It has been found that zinc chromate primer, which is in common use as a primer material for the purpose, dispersed in an evaporable-oil-dissolved resinous film-former provides an excellent corrosion-inhibiting liquid for application between the faying surfaces of these metal plates, and has been used before by brush or other application directly to the surfaces. The inconvenience and sloppiness of hand application of the wet material, its drying, and its even, economical, and sufficient application in each case of use with a rivet which has not received the pustular-capsule treatment of this invention cerated a need in the art which this invention fulfills in a dramatically efficient manner.

Encapsulation of oily fluids which are liquids with or without a solid dispersed matter in them, or liquids with protective matter in solution, has been known for some years, and various methods of encapsulation have been devised wherein minute capsules ranging from microsized capsules (one micron to twenty microns) up to larger sizes in the megascopic or minute range of 250 to 400 microns are formed en masse. These encapsulation processes for the most part, in the most impermeable form as far as the retention of volatile oily liquids is concerned, commenced with the invention disclosed in U.S. Patent No. 2,800,458, which issued to Barrett K. Green on July 23, 1957, and which was reissued as Reissue Patent No. 24,899 on Nov. 29, 1960, and as simultaneously disclosed in U.S. Patent No. 2,800,457, which issued to Barrett K. Green and Lowell Schleicher on July 23, 1957. The two patents disclose on one hand the use of a single polymeric capsule wall material in a process in which a coacervate solution thereof was caused to emerge as a separate liquid phase from a homogeneous aqueous solution as a liquid wall-forming phase, and on the other hand the use of two polymeric materials which were caused to complex and emerge by a different mechanism from a homogeneous solution as a coacervate liquid phase. Both types of emergent phases are subject to dispersion in the manufacturing residual vehicle and are capable of forming walls about introduced dispersed droplets of oil. At that early time, the process of making capsules was concerned with the making of micro-sized capsulesthat is to say, those that cannot be individually recognized by the unaided eye; but since that time means have been found to successfully and effectively produce large capsules of the order of 250 to 500 microns, and larger, with the same facility and having similar properties. Among such means are those disclosed in the following U.S. patents:

(1961) 2,969,330which relates to capsule walls produced by a polymerizing step.

(1961) 2,969,331which relates to a process for making artificial-polymer-walled capsules surrounding a wall of natural polymer material.

(1962) 3,041,288--which relates to capsules made of alcohol-fractionated gelatin.

(1962) 3,041,289-which relates to capsules made with multiple droplets of oil inside.

(1962) 3,069,370which relates to capsules made with styrene maleic acid wall material.

(1965) 3,190,837which relates to large single oil drop capsules with rather thick walls.

These and many other methods of making capsules are available for encapsulating oil, oily solutions, and oildispersions of protective material, among the most serviceable of which in connection with aluminum plates and rivets to be fastened together being those which contain zinc yellow dispersed in an oily evaporable material such as toluene or xylene, with or without supplementary ingredients. This type of dispersion is commonly used with a binder material of some kind to form a primer, which, before the provision of this invention, was coated directly on surfaces to be protected. The dispersed pigment breaks down in the presence of water to give a residual product which is very effective in its anti-corrosion or corrosionpreventing properties. Other protective materials such as air-excluding oils, water-excluding oils, and any of the non-aqueous media of liquid state which are used to protect materials from the environment come within the scope of use of the means of this invention. Some of these protective materials may have other uses while acting as a protective material. Among such other properties are those of lubrication to assist in removal of the fastening; sealant in preserving the fastening against removal; an indication of the state of the joint of the fastening; a coloridentification of fastening points; and any other preparatory or preservative action.

The invention will be described in conjunction with the drawings, which are illustrative of the structure claimed in a diagrammatic manner to bring out its salient points. Of the drawings:

FIG. 1 is a diagrammatic part section, part elevation view of the construction of the invention as it appears upon a surface of a fastening. This view is intended to show the relative proportions between the thickness of the adhesive film to which the capsules are applied and in which they are partially embedded; the capsules themselves as to differences in size, which is of a random nature; and the thin veil-like abrasion-resistant film, which, too, is of minor dimension in thickness with respect to the size of the capsules, so as to assume a draped effect, leaving the capsules represented by knobs protruding from the Vail-like film, where they are subject to pressures from all sides and are non-resistant with respect to side support, so that they may be easily crushed to release the liquid contents. Even in this view, the thicknesses of the films are exaggerated with respect to liquid droplet size.

FIG. 2 is a section through a headed rivet, showing the pustular protective construction on its faying surfaces, in condition to be ruptured by being pressed against the accommodating aperture in the piece to be fastened, and available upon the upsetting of the end of the shank of the rivet to become broken as the upset end of the rivet andthe shank surfaces meet the surfaces of the piece to be fastened in the faying relation. This view too is exaggerated, as it shows the capsules larger and the adhesive coat thicker than is true with relation to the fastening dimensions.

FIG. 3 is a section through a metal plate lap joint fastened by a screw bolt and nut with the pustular layer broken to release the liquid primer.

FIG. 4 shows a tapered drift pin having the capsule construction on the surface, said pin being adapted to be hammered into an accommodating hole, as for fastening a wheel by its hub to an arbor, FIG. 5 shows a threaded screw with the capsule treatment in the grooves and on the under side of the head thereof, FIG. 6 shows a headed nail similarly treated, and FIG. 7 shows a cylindrical spreading-collar type of pin so treated.

The capsules may be spaced by being supplied in such limited numbers that they are not in actual contact sidewise with one another when randomly dusted on the fastening, which spacing provides for easier rupturing and more efiicient use of the released liquid. On the other hand, if desired, the capsules may be packed close together and used in greater numbers to deliver a larger quantity of liquid per area of faying surface involved as the occasion demands.

The adhesive layer material, the capsule wall material, and the outer protective layer material must be compatible chemically and physically with each other. From an economic standpoint, these material should be readily available, easily applied, and physically durable as to environment, including excessive humidity and dryness and excessive deviation from room temperature, as would be encountered in the polar regions, the equatorial regions, outer space, and the less rigorous but atmospheric stratosphere. The materials should be proof against vibrational stress, biological attack, and environmental radiation. To these ends, the adhesive layer material chosen for the preferred embodiment is a lacquer comprising an alkyd resin dissolved in a readily-evaporable organic liquid solvent, which lacquer may be applied to the fastening by spraying to give a light, evenly thick layer which becomes sufiiciently tacky by reason of solvent evaporation to receive and hold the dusting of capsules within a minute or so of application and which, after having the capsules dusted thereon, may be set to a hard condition by oven-heating at 140 degrees Fahrenheit, more or less, for a few minutes. The preferred protective coating is an acrylic resin lacquer with a readily evaporable solvent which is dissipated in a few minutes at the named oven temperature, to leave a thin but horn-like layer of the resin draped around the contours of the capsules that previously have been dusted on the tacky adhesive coating.

EXAMPLE I This example concerns the use of a liquid primer as the capsule contents, including a liquid vehicle in which the composition zinc yellow is dispersed as an anticorrosion ingredient. The primer contains, in addition to the zinc yellow, an adhering protective film material dissolved in an oily solvent that is readily evaporated to cause the primer to set quickly once it is not protected by the capsule walls. This primer is encapsulated in an organic film-forming polymeric material 28 (FIG. 1) in an en masse process in a liquid manufacturing vehicle system consisting of the polymeric material in solution and the primer particles to be encapsulated. The polymeric material, in this solution of the preferred embodiment, consists of several types of molecules which are caused to form a complex and emerge from the solution as a viscous liquid coacervate phase of such character as will break up as tiny droplets which wrap around nucleus particles which may be dispersed within the vehicle when the system is agitated. This wrapping forms liquidwalled capsules, and the walls are set to a firm state by apropriate means. For a batch made in a four-liter vessel, add to 2,750 milliliters of distilled water 42 /2 grams of acid-extracted pigskin gelatin having a high Bloom strength and having a normal pH of 3-4 and its isoelectric point at pH 8-9. This is stirred at 50 degrees centrigrade and, while it is being stirred, grains of sorbitol is added and dissolved. Thereupon a 20%, by weight, aqueous solution of sodium hydroxide is added to bring the pH to 7. In a second vessel, add 3 grams of carrageenan to 600 grams of distilled water to form a solution having a normal pH of 7-9. This is warmed and stirred until a completely homogeneous solution results. In a third vessel are mixed the following:

Grams Zinc yellow 35.6 Talc extender (magnesium silicate) 61 Drying-type of modified alkyl resin (medium linseed oil alkyl resin) l8 Dispersion resin (a butyrated phenolic-formaldehyde copolymer with 50% China wood oil) 11.5

Xylene 50.8

The xylene content is adjusted to give a viscosity of 27 centipoises at 77 degrees Fahrenheit, and the temperature of the system is adjusted to 23 degrees centigrade. From the contents of the third vessel, an amount of 128 grams is mixed into the first vessel with agitation sufficient to create of it a drop size with a range of to 300 microns, the temperature being kept at 50 degrees centrigrade. The contents of the second vessel, then is added to the agitated system of the first vessel, drop by drop, over a period of thirty minutes, to form the liquid-walled embryo capsules. The first vessel then is cooled on an ice bed until the system reaches 10 degrees centigrade in a period of about three hours, whereupon the liquid capsule walls have gelled to a self-supporting condition, and the capsules therefore are in a state to be recovered from the remaining contents of the vessel by decantation and filtration. The filter cake, composed of an aggregate of capsules, is dispersed in several liters of hexelene glycol at room temperateure (20 to 25 degrees centigrade), and the capsules are filtered out, washed with several liters of toluene, and air-dried under a hood after having been spread on an absorbent sheet.

To obtain the exact size of capsules that is wanted for the particular use, the dry capsules are classified on appropriate screens. As before mentioned, a selection of those of the order of 250 microns as a maximum is most suitable for use on manually-positioned rivets.

A thin lacquer or varnish is sprayed on the rivets faying surfaces to form a layer 29, the varnish being of a type that first dries by evaporation to a tacky state and then dries or oxidizes to a hard state, as is the case with the specified alkyd resin lacquer mentioned above. The capsules are applied to the tacky coating as a dusting, and then the curing is carried out in a l40-degree-Fahrenheit oven for ten minutes or so, according to standard practices in curing such alkyd resin coatings. The rivets may be held on appropriate jigs in an array, so that their faying surfaces are exposed for a spraying operation. The cap sules, embedded part-way into the lacquer layer, are next subjected to the overlayer 30 of a protective material, for instance, by spraying thereon a toluene solution of butylmethacrylate copolymer to leave, when dried, a residue one mil in thickness in the form of a veil-like film draped on and around the embedded but protuberant capsules. This thin draped veil or film protects the capsules against brush-off and abrasion. The draped film layer is dried by evaporation, assisted, if desired, by the heated atmosphere in the l40-degree-Fahrenheit oven.

Although this example has been described with respect to rivets, the same procedures, of course, are followed when the compound layer material structure is installed on other types of fastenings shown in the drawings (FIGS. 3-7

F rom the foregoing, it will be apparent that it is not the materials used which are of paramount importance, but it is the arrangement of the materials on the fastenings, so as to provide the protected but easily-rupturable capsular pustular coating.

EXAMPLE II In this example, there is used, as the capsule contents, a lubricating petroleum oil in place of the zinc yellow primer liquid described in Example I. Capsules with an oil content may be made as disclosed in US. Letters Patent No. 2,800,457, which issued July 23, 1957, on the application of Barrett K. Green and Lowell Schleicher. In that patent, aqueous solutions of gelatin and gum arabic are individually made and mixed with oil to form a homogeneous dispersion of the solution and undissolved included oil droplets, the emergence of a coacervate phase being provided for by changing the conditions of the system, wherein the coacervate phase, which is a liquid, is caused by agitation of the system to wrap itself around emulsion-sized droplets of oil to form liquid-walled embryo capsules that thereupon are chilled, so that they may be recovered from the system and dried. These capsules may be hardened to resist temperature effects on a gelatin material, as by use of a formaldehyde solution or any other gelatin tanning or cross-linking agents. These capsules may be made of microscopic size and in sizes which may be described as megascopic, as determined by the degree of agitation of the system, all as is Well known in the art of encapsulation. The dry capsules may be used as a dusting to the tacky-adhesive coated surface of the fastening and permanently secured thereto by causing the adhesive material to set. The over-draped material is then applied to form the pustular construction noted in Example I. The oil may be of lubdicating character only, or may contain additives in the way of wetting agents to promote their flow or to supply any other added characteristic. Here, as in Example I, the feature of the invention is the pustular construction.

8. EXAMPLE III In this example of the invention, the raw materials (that is to say, the polymeric material which envelops and retains the liquid contents of the capsules, or the liquid contents of the capsules), whether consisting totally of the materials specified in Example I or totally of the materials specified in Example II, or mixtures thereof, may be colored, as by dyes or pigments to serve as proof of the presence of those materials in a joint, either before or after rupture of the capsules. The wall material contents shall be colored with either a pigment or a dye suitable to the situation. Not only may the capsule walls be colored differently according to the contents identification, but the capsule contents may be colored to afford mere proof of rupture of the capsule and release of its contents and its extent of spread upon the faying surfaces to be joined. For oil-solubility, an oil-soluble dye such as Sudan (Red) III, Quinizarin Green SS (bluish green), or Yellow OB (reddish yellow) can be used, or, if the coloration is to be brought about by development of a leuco type of material, then Crystal Violet Lactone might be used. There are many water-soluble food dyes, such as Erythrosine (bluish pink), Orange II (bright orange), and Tartrazine (greenish yellow), which may be used when water-solubility is necessary, as when the polymeric material is watersoluble and it is desired to dye or color the capsule walls with the water-soluble dye or coloring material. Instead of dye, the coloring material may be of any of the paint pigments if. opaqueness is desired.

EXAMPLE IV In this example, it is provided that a radioactive material be used as a tracer material to afford the manifestation of a characteristic radiation spot wherever the capsules happen to be located in a workpiece, to make proof that such capsules are present in the fastenings or in the fastened workpieces. With regard to the radioactive tracer material, it is to be understood that this can be applied either in the contents of the capsule, in the wall of the capsule, or in both the contents or the walls of the capsules or the layers. It is provided that the presence of the pattern of the released protective material can be sensed by radiation-sensitive film material or other sensing means. Where a suspected workpiece is to be examined, the radiation may be sensed where the faying surfaces cannot be seen because of being hidden within the body of the workpiece. Among such radioactive materials suitable for use are the tracer materials carbon 14, which may be used with xylene, or tritium tagged to gelatin.

EXAMPLE V In this example, it is provided that any one of the capsule-forming materials or the film materials be supplied with a fluorescent material which is responsive to either or both the visible and the invisible electromagnetic radiation bands included in the range from ultraviolet through the infrared, to permit the sensing of the presence of the material in a joint by its luminosity rather than by its reflective characteristics; Rhodamine B is exemplary of a water-soluble fluorescent dye for use in the aqueous-soluble components, and Rhodamine B base is suitable for solution in organic solvents.

The materials which may be substituted for alkyd lacquer of the adhesive coating are shellac (alcohol solvent), methyl methacrylate (toluene solvent), or any other solvent drying varnish or lacquer.

The over-coating film-forming material which can be substituted for the acrylic solution part of the construction are solutions of alkyd resin, nitrocellulose, polystyrene, polyethylene, and vinyl chloride.

FIG. 3 shows a bolt-type of fastening holding two plates 31 and 32 together, with the exuded protective material 33 positioned between the faying surfaces.

9 10 What is claimed is: to the capsule size and which conforms to the outer aspect 1. A fastening meant to be fastened in a workpiece by of the dusting to provide an exterior surface of proforce which brings faying surfaces of the fastening and tuberant knobs of capsules. the workpiece into jamming-pressure contact, including (a) a dusting of freestanding protective liquid-containing 5 capsules of minute size arranged in close proximity but UNITED STATES PATENTS not packed together on the fayiug surface of the fasten- 3,061,455 10/1962 Anthony 151-145 ing, said capsules being embedded slightly in a binder of film material to preserve the arrangement until use, and RAMON BRHTS Pmnary Exammer (b) a draping of a film of protective material on the 10 5 1 outer aspect of the dusting (a) which is thin with respect 5 10 37 References Cited 

